Electroplating



United States Patent ass1,1z1 ELECTIROPLATING Donald G. Foullre, Watchlmg, Otto Kardos, Red Bank, and Herman Koretzky, Belleville, NJ, assignors to Hanson-Van Winkle-Munning Company, a corporation of New Jersey No=Drawlng. Application March 14, 1957 Serial No. 645,922

11 Claims. (Cl. 204-52) This invention relates to electroplating and, more particularly, to electrodepositing copper from an aqueous alkaline cyanide copper plating bath. The invention is based on our discovery that both alkali-soluble trivalent bismuth compounds and water-soluble acetylenic compounds, when incorporated in a copper plating bath in conjunction with selenium compounds, are capable of promoting the formation of excellent bright and ductile electrodeposits of copper over a wide current density range.

The electrodeposition of copper from an alkaline cyanide plating bath containing only an alkali-soluble selenium compound as the brightening additive generally produces electroplates which are bright over a relatively narrow current density range, e.g. between 2 and amperes per square. foot, while. semi-bright and even hazy deposits are. formed at current densities below and above these limits. When, however, a small quantity of either an alkali-soluble trivalent bismuth compound or a watersoluble acetylenic compound is incorporated in the plating bath together with a selenium. compound, the brightening capacity of the bath is markedly extended, and the. electrodeposit is bright andv frequently brilliant over a very wide current density range.

The brightening capacity may be extended still further by adding certain nitroxy compounds to the plating bath. These. compounds are effective in alkaline copper cyanide baths which contain a bismuth compound, an acetylenic compound, or a titanium. compound in addition to a selenium compound. The nitroxy compounds extend the bright current density range to a remarkable degree.

The. process of our. invention. is accomplished most advantageously-by using an alkali cyanide copper plating ibath, in which both the concentration of copper and of cyanide, as well as. the ratio of copper concentration to cyanide concentration, are within. the limits generally employed for standard copper electroplating operations. Such baths usually contain from 20. to- 75 grams per liter of copper and from 45 to 145 grams per liter of an alkali metal cyanide. In this plating bath; we generally employ from 0.01 to 20 millimoles per liter of an alkalisoluble selenium compound, and from about 0.005 to about 200 millirnoles per liter of the bismuth. compound or acetylenic compound (or titanium compound, when a nitroxy compound is also. present). A nitroxy compound can be used..withadvantage. in combination with either a bismuth compound or an acetylenic compound, as well as in combination with a titanium compound. In addition small quantities of auxiliary compounds, such as various. nitriles and water-dispersible wetting agents, may also be. incorporated in the bath.

In the case of the trivalent bismuth compounds, only relatively small quantities are required in the plating bath, especially when they are used in. coniunction with a selenium brightener. In general, concentrations of. the trivalent. bismuth compound as low as 0.005 millimole 2,881,121 Patented Apr. 7, 1959 per liter (0.002 gram per liter of bismuth) are effective, though for optimum results it is usually preferable to employ at least 0.025 millimole per liter. In general the trivalent bismuth compound may be used over a relatively wide range in concentrations, but there is no great advantage in using more than about 1 gram per liter, and in most plating baths substantially the full benefit of its presence is achieved with concentrations of 0.02 gram per liter or even less.

Any trivalent bismuth compound capable of being dissolved in weakly alkaline media may be successfully employed in the plating bath. Various bismuth salts, such as bismuth citrate, bismuth subsalicylate and bismuth tartarate, have been used successfully, but most bismuth salts are insoluble or dissolved with great difliculty in alkaline solution. We have obtained particularly satisfactory results using a trivalent bismuth coordination compound having at least one ligand selected from the group consisting of polyols and hydroxycarboxylic acids. These compounds are soluble in water and generally stable in alkaline solution. They may be prepared by slowly adding a bismuth salt to an aqueous solution of the polyol or hydroxycarboxylic acid. Although the precise structure of the coordination compound is unknown, the cluster of hydrophilic ligands surrounding the hismuth nucleus allows the complex to be solvated by water. Thus, bismuth coordination compounds containing ligands of hydroxycarboxylic acids, such as gluconic acid, or those prepared from polyols such as sorbitol and glycerol, are particularly efiective when incorporated in the plating bath with an alkali-soluble selenium compound.

When an acetylenic compound is used in the bath, it preferably is above 1 millimole per liter, and for optimum results it is usually preferable to employ at least 10 millimoles per liter. There appears to be no critical upper limit to the concentration of the acetylenic compound save solubility, but there is no great advantage in using more than about 200 millimoles per liter, and in most plating baths substantially the full benefit of its presence is achieved with millimoles per liter or even less.

While any water-soluble acetylenic compound may be employed in the plating bath to produce bright copper deposits in accordance with the invention, we have obtained particularly satisfactory results using either oxygen-containing acetylenic compounds (especially acetylenic alcohols) or acetylenic amine compounds. Compounds from among the oxygen-containing acetylenic group which have been found to be very satisfactory are those which have the formula- RI Rr-dl-CEC-Rs in which R,, and R, are substituents selected from the group consisting of hydrogen and alkyl and hydroxysubstituted alkyl radicals, R, is a substituent selected from the group consisting of hydroxy, hydroxymethyl, methoxy, hydroxyethyl, ethoxy, and hydroxyethoxy radicals, and R is a substituent selected from the group consisting of hydrogen, halogen, diethylaminoethyl, morpholino methyl, alkyl, alkenyl, alkynyl, and hydroxy-, methoxyand ethoxy-substituted alkyl, alkenyl, and alkynyl radicals. When used in the plating bath in conjunction with a selenium compound, these water-soluble oxygen-containing acetylenic compounds produce bright electrodeposits at current densities ranging from 1 to 100 amperes per square foot.

The acetylenic amines function particularly effectively at the higher current densities. As a general rule, the acetylenic amines are less soluble in an alkaline is particularly satisfactory, and aldoxime and dimethylglyoxime are examples of satisfactory oximes.

However, any such nitrojxy compound, which is capable of being dissolved in weakly alkaline media and does not undergo decomposition in the presence of hydroxide ions may be successfullyfemployed in the plating bath. We generally prefer to employ a nitroxy salt of an alkali metal, i.e. an alkali metal nitrate or nitrite; and, we have found that in'general'the full-benefit of their. presence is achieved with amounts in'the range fro'm'7.5-to 45 grams Perliter. 1-

In all, three classes of secondary brightener addition agents have been successfullyemployed in the plating bath in conjunction with a selenium primary brightener ad- TABLE I Water-soluble acetylenic compounds for bright copper plating Compound Structure 2-Bu e-14-dl0l HO'OH OEC-OHsOH Propz gylnleohol Bozo-011,011 Dipotassium'acetylsnedicarboxylate KOOO-OEO-OOOK 1.4-Dimethoxy-2-butyue HsCOCHsCEOCHsOOHs 2,4-H6xadiyne-L6-diol HrCEC-CEO-CHsOH 1- N.N-dlethylamino)-2-butyn+ol. OHsHs)sN-CHsQEGCHsOH 3 m 28 E ll -0 s i-Met r r l-a-hydro ethoxy-1-butyne..-.. HrO-O OH: UCsHlO 050E a g hrll-bugn ol 1558 5! gimme 8 am 0 s lA-RQ'fR-diethzaminQ-Q-butyn gOHKJHEN-OHsCEOOHsNwHsOKsJ S-Amlnodmet yl-i-butyne... H1020 )(NH )CECH 8-Alnlno-3-othyl-l-butyne omo olmxrrnnozon Selection of a selenium "primary" brightener addition agent for inclusion in the plating bath may be made from either organoselenium compounds or selenium salts, including selenides, selenites, selenates and selenocyanates. Although these selenium compounds may be used over every wide range of concentrations, they are preferably employed in an amount'to yield from 0.001 to 0.5 gram per liter of selenium; or, expressed in equivalent weights, we use from about 0.01 to about millimoles of the selenium compound per liter.

it is generally possible to improve the brilliance of the electroplates, and to further broaden the current density range over which bright deposits are formed, by incorporating a small amount of an alkali-soluble nitroxy compound in the plating bath. When employed in a plating bath with a selenium compound and a bismuth compound or acetylenic compound, or an alkali-soluble titanium compound, the nitroxy compound extends to a remarkable degree current density range over which bright deposits can be formed. The nitroxy compounds employed all contain, as their common structural feature, an ionic v moiety represented by the formula a=N-O in which a is an atom selected from the group consisting of oxygen and disubstituted carbon atoms, and p is a member of the group consisting of an electron pair and a coordinately bonded oxygen atom. Thus, when a is arr-oxygen atom, the nitroxy compound may be either an inorganic nitrite (p=an electron pair) or an inorganic nitrate (fi=a coordinately bonded oxygen atom), since these..-compounds dissolve in alkaline solution to form nitrite and nitrate ions respectively. On the other hand. when a is a disubstituted carbon atom, the nitroxy compound may be either an oxime (p-an electron pair) .or a nitroalkane (flue coordinately bonded oxygen atom). When organic nitrates and nitrites are used, they should be-salts whose cations do not precipitate in the alkaline cyanide solution and do not exert any deleterious. efiect. Especially satisfactory nitrates and nitrites are-those of the .alkalhmetals, magnesium, ammonium and copper. Among the nitroalkanes-that may be used, nitromethane oxyethylene or polyoxypropylene glycol,

ditive andthe nitroxy compound. These include, in addition to the previously mentioned alkali-soluble trivalent bismuth compounds and alkali-solubleacetylenic compounds, the alkali-soluble titanium compounds which are described in the copending application of Donald G. Foulke and Otto Kardos, Serial No. 582,661, filed May 4, 1956, now United States Patent No. 2,848,394, granted August'l9, 1958.- Included among the titanium compounds capable of being dissolved in weakly alkaline media and which can-be used in combination with a selenium compound and a nitroxy compound are various titanium salts, such as potassium titanate, titanium lactate and potassium titanium oxalate, in which the titanium moiety may be'either in the cationic'o'r anionic portion of the compound. Particularly satisfactory results have been obtained, however, using titanium coordination compounds having at least one ligand which is a polyol or alkauolamine. These titanium coordination compounds are soluble in water and generally stable in alkaline solution; they are prepared by condensing a titanium halide together with an alkoxide of the polyol or alkanolamine. Although the titanium compounds may be employed in the bath in concentrations as low as 0.005 and as high as 200 millimolesper liter, they are preferably used in Eogocntrations ranging from 0.5 to 25 millimoles per The lustre and brilliance of the electroplate and the range of optimum plating conditions may be still further broadened by incorporating a small amount of various auxiliary agents in the plating bath. Wetting agents are among the most useful of these auxiliary agents. We have had particular success by adding to the plating bath a polyoxy compound having the formula Bl Rr-{OHsiiH-Oh-Rr v in which R; is a substituent selected from the group consisting of hydrogen and methyl, R and R; are substituents selected from the group consisting-of hydroxy, alkoxy, thioalkoxy, phenoxy, alkylphenoxy, thiophe'noxy, alkylmercapto, and carboxamido, and n is an integer from 6 to 60. These polyoxy compounds areyof'course, polysnd the condensation products of ethylene or propylene oxide. together with alcohols, thioalcohols, phenols, thiophenols and amides. The polyoxy compound may be added at any time during the preparation of the plating bath, and may be used in concentrations in the range from 0.05 to 20 grams per liter.

Alkali-soluble nitriles are examples of other auxiliary brightening agents which may be successfully employed in the plating bath together with either a bismuth or an acetylenic compound and an alkali-soluble selenium compound. Table H sets forth several examples of such nitriles which have been used successfully in embodiments of this invention. The concentration values set opposite each compound inTable II were found to give good results when that compound was used in combination with an alkali-soluble primary selenium brightening compound and either a trivalent bismuth compound or an acetylenic compound. These concentrations, however, do not necessarily indicate optimum, or maximum or minimum concentrations. In general, from 0.05 to 20 grams per liter of an alkali soluble nitrile may be used in the bath.

6 Indeed, the brightening agents described above function particularly well in a sodium plating bath, especially at the higher concentrations of copper and at higher temperatures.

'Iable HI illustrates the efiect exerted by trivalent bismuth in extending the brightening capacity of a copper plating bath containing a selenium "primary" brightener. This table summarizes a series of tests which were carried out on a typical plating bath containing a representative alkali-soluble selenium compound, alone and in combination with a trivalent bismuth compound. In each of these particular examples, a typical alkaline cyanide copper plating bath, containing 48 grams per liter of copper (as metal), 9 grams per liter of free potassium cyanide, grams per liter of potassium hydroxide, and- 30 grams per liter of potassium'sodium tartarate, was used. Plating operations in each example were carried out in a Hull test cell so that the efiect of a wide range of current densities could be observed. The electrodeposits were formed on brass cathodes at a temperature of 150' F.

TABLE III Efiecr of trivalent bismuth additives on bright copper 9 s 0on0. Bismuth Selenium Compound (Gm/l.) Tartar-ate Character-Deposit (Gm-IL) H b it in of the current a 1 Wm 0- density r ge mo tire d t W W mastsaasana my W m 0.08 8am t horn 3-12 s.s.l. PM 0.01; 0.005; ml brightness intensity over the entire current enslty range; 2 br ght from 2-8 a.s.t.

0.0M- Milky-andsemi-b tovermostolthecurmntdensity 0.064 0.0054 lnc'eased intensity in brightness, and especially in 0.0: H2; and ssinir iglit d t d about 14 a s r 0.02 0.00m improved brightness wl h considerably iss haze over entire current density range.

l As the sorbltol complex. TABLE 11 Examples I to IV below illustrate the efiect exerted by water-soluble aeetylenic compounds on the brightening 8 P Plating capacity of copper plating baths containing selenium Gm per liter compounds. Table IV lists the basic compositions of two succinonimle (L05 to Q5 plating baths which were employed to carrying out these Dicyandiamide o 12 and other examples of the invention that are set forth "'7'.- '1" 3,13 -0xydlpropriomtnle 0.12 Potassium dicyanoguanidine 0.12 TABLE Iv p-Sulfopropionitrile 0-12 Bath concentrations in grams per liter Sodium dicyandiamide 0.12

A conventional alkaline-cyanide copper plating bath, 66 Bath to which the primary, secondary and auxiliary brightening agents may be added for making up a plating bath ggm ag' fi 1;; 9g 73 in accordance with this invention, customarily has the g 73 35 $8 8 following composition;

- go In each of the following examples demonstrating the Gm effect of the acetylenic compounds, the elcctrodeposit was Gallon formed ma Hull test cell so that-the cfiect of a wide range 3f culrrenzdtiensities could be observed. In each case, 00 per(asmetal stolo am 16 e c ctr posits were formed on brass cathodes at ggggig 5 ,333}: R ffi as emp a u s. varying between. 60 and 68 C., with agio'tasslum sodium tartarate aloe 151.046 tatlon provided where indicated. Potassium ctu'bonate 03.0 lb 0- ,HO

EXAMPLE I The tartarate (Rochelle salt) and carbonate, while preferred, are optional ingredients and can be omitted. Although salts may be used interchangeably for the potassium salts, the. use of the potassium plating bath has found increased favor in recentyears. The addition agents described in the invention, however, are equally applicable to both sodium and potassium plating baths.

7 Upon the-addition mt lgram=per liter otZ-butyne- 1,4-diol to this batln a very bright deposit was obtained under identical plating conditions: over -a current density range between and 20 amperes per square foot. When air and mechanical agitation were provided, bright deposits we're obtained'yb'etween l0rand- 40amperes per square foot.

vminimum: 11-;

.Using a standard copper-platingibath (Bath A) which contained 0.13 gram per/liter of sodium selenite, a

bright electroplatewas deposited between 2 and l0 am peres per square toot on the test-panelin a Hull cell operated at 681C. When 1 gram-per liter of 2-butynel,'4"diol was added bath, .a bright deposit was obtairzed over the .l'g'we st observable current sodium selenate was used'in the bath in place of -potassium selenocyanate. By adding 1 gramper liter of 2-butyne-l,4-diol to the bath, the electrodeposit was fully brilliant from the lowest observable current density to 20 amperes per square foot.

EXAMPLE IV The acetylenic compounds have also proved exceptionally efiective in copper plating baths containing selenide brightening additives. Using a standard copper plating having the basic compositionof Bath B and containing 0.002 gram per liter of sodium'selenide and 1 gram per liter of 2-butynel,4-diol, deposits formed on test panels at a bath temperature of 68 0., without agitation, were fully bright current densities from the lowest observable value was amperes per square foot. Similarly, when 0.45 gram per liter-of propargyl alcohol was added to the bath in place of 2-butyne-l,4-diol, and the concentration of sodium selenide increased from 0.002 to 0.004 gram per liter, a bright copper electroplate was formed, without agitatium over the current density range from the lowest observable value to 20 amperes per square foot. The substitution of other acetylcnic compounds, notably 2-methyl-3-butyn-2-ol, 2,4- hexadiyne-Ld-diol, dipotassium acetylenedicarboxylate, dimethyl ester of Z-butyne-LMicarboxylic and 3-methyll-butyn-S-ol in equivalent amounts, also produced bright copper deposits at all current densities up to 20 amperes per square foot.

The efiect exerted by the nitroxy compounds in extending the bright plating range was demonstrated in a series of tests carried out using typical plating baths containing representative primary and secondary brightening agents, with and without the addition of an alkalisoluble nitroxy compound. In each of these tests, which are set forth in Example V through IX, a plating bath having the composition of Bath A of Table IV was used. As before, "plating operations in eachof these examples were carried out ina standard Hull-test call so that the effect of a wide range of current densities could be observed. The electrodeposits were formed on brass test panels at a temperature of '68"C.' and without agitation.

To the standard copper plating bath was added 0.003 gram per liter of potassiummelenocyanate and 0.003 gram per liter of bismuth trioxide (as the tartarate complex). A test panel which received a copper electroplate from this bath was bright over a current density range from 1 to.8 amperes per square foot, but exhibited slight haziness in the middle current density range. Upon-the addition of 30 grams per liter otpotassium .nitrate tothis bath, the resultant electroplate was exceptionally bright in the-current density 'range from 12 to 50 amperes per 'per square foot." y Identical results were obtained when 0.005 gram per liter of bismuth trioxide (as the sorbitol complex) was used'in the 'platings'olution in combination with the potassium selanocyanate and potassium nitrate.

' EXAMPLE v1 Brilliant copper deposits are formed when the primary and secondary-brightening agents are used in conjunction with an inorganic nitrite. The test panel of a Hull cell received a copper electrodeposit from the standard copper plating bathwhichcontained 0.003 gram per liter of potassium selenocyanate and 0.003 gram per liter of bismuth trioxide: (as the tartarate complex). The plated panel wasbrig'ht at 'thelow currenhdensity end (1 to 12 amperes per square foot). Upon adding 30 grams per liter of potassium nitrite to this bath, the copper deposit formed was exceptionally bright over the current density range corresponding to 12 to 50 amperes per square foot, and about as bright as before the nitrate addition below 12 amperes per square foot.

EXAMPLE VII To a standard copper plating bath were added 0.064 gram per liter of sodium selenite and 8.8 millimoles per liter of [(N-hydroxyethyl-diethanolatoamine-0,0',N) (sorbitolato-0,0',O")J titanium (IV), and copper was electrodeposited on a Hull test panel. The deposit was bright over a current density rangefrom l to 8 amperes per square foot, representing 35 percent of the panel. Upon the addition-of 30 grams per liter of potassium nitrate to this bath, a brilliant electrodeposit was obtained over the entire panel, corresponding to a current density range from 1 to 50 amperes per square foot.

In a comparative operation, the substitution of 30 grams per liter 'of potassium nitrite for the potassium nitrate yielded identical results.

EXAMPLE VIII Using the standard copper plating solution to which 0.003 gram per liter of potassium selenocyanate and 1 gram per liter of '2-butyn-l,4-diol had been added, a bright copper deposit was formed on a test panel in a Hull cell throughout the current density range from 1 and 22 amperes per square foot, covering about threefifths of the panel. When, however, 30 grams per liter of' potassium nitrate were added to this bath, the electrodeposit was brilliant over the full width of the panel,

corresponding to a current density range from 1 to 50 amperes per square foot. Both potassium nitrite and sodium nitrite gave'identical results when substituted for the potassium nitrate.

EXAMPLE 1x A cumulative brightening etIect is also exerted on the plating bath when an oxime or nitroalkane is used in place of an inorganic nitrate or nitrite. These organic nitroxy compounds are somewhat susceptible to hydrolysis but the efiect of base hydrolysis may be substantially avoided by operating the cell at lower temperatures (say near room temperature).

Using the standard copper plating bath which contained 0.003 gram per liter of potassium selanocyanate We claim:

1. A process for producing a bright copper electroplate which comprises electrodepositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.01 to 20 millimoles per liter of an alkali-soluble selenium compound and from 0.005 to 200 millimoles per liter of a water-soluble acetylenic compound.

2. A process for producing a brishti ppet electroplate which comprises electrodepositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.001 to 1 gram per liter of selenium added in the form of an alkali-soluble selenium compound, and from about 0.01 to about 100 millimoles per liter of a water-soluble acetylenic compound.

3. A process for producing a bright copper electroplate which comprises electro-depositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.001 to 1 gram per liter of selenium added in the form of an alkali-soluble selenium compound, from about 0.01 -to about 100 millimoles per liter of a water-soluble acetylenic compound, and from 5 to 60 grams per liter of an alkali-soluble nitroxy compound which, upon dissolving in alkaline solution, contains an ionic moiety represented by the formula a c-I I-O in which a is an atom selected from the group consisting of oxygen and disubstituted carbon atoms, and p is a member of the group consisting of an electron pair and a coordinately bonded oxygen atom.

4. A process for producing a bright copper electroplate which comprises electro-depositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.001 to 1 gram; per liter of selenium added in the form of an alkali-soluble selenium compound, from about 0.01 to about 100 millimoles per liter of a water-soluble acetylenic compound, and from 5 to 60 grams per liter of an alkali-soluble nitroxy compound selected from the group consisting of nitroalkanes, oximes, and nitrates and nitrites of alkali metals, magnesium, ammonium and copper.

5. The process for producing a bright copper electroplate which comprises electrodepositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.01 to 20 millimoles per liter of an alkali-soluble selenium compound and from 1 to 200 millimoles per liter of a water-soluble acetylenic compound.

6. The process for producing a bright copper electroplate which comprises electrodepositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.01 to 20 millimoles per liter of an alkali-soluble selenium compound selected from the group consisting of selenides, selenites, selenates, and selenocyanates, and from 1 to 200 millimoles per liter of a water-soluble acetylenic compound.

7. The process for producing a bright copper electroplate which comprises electrodeposin'ng copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.01 to 20 millimoles per liter of an alkali-soluble selenium compound and from 1 to 200 millimoles per liter of a water-soluble acetylenic compound having the structure arses...

in which R. and R; are substituents selected from the group of hydrogen and alkyl and hydroxy-sub stituted alkyl radicals, R, is a substituent selected from the group consisting of hydroxy, hydroxymethyl, methoxy, hydroxyethyl, ethoxy, and hydroxyethoxy radicals, and R is a substituent selected from the group consisting of. hydrogen, halogen, diethylaminoethyl, morpholinome'thyl, alkyl,- alkenyl, alkynyl, and hydroxy-, methoxy-, and ethoxy-substituted alkyl, alkenyl, and alkynyl radicals.

8. The process for producing a bright copper electroplate which comprises eleetrodepositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.01 to 20 millimoles per liter of an alkali-soluble selenium compound selected from the group consisting of selenides, selenites, selenates, and selenocyanates, from about 1 to about 200 millimoles per liter of a water-soluble acetylenic compound, and from about 5 to about 60 grams per liter of a nitroxy compound selected from the group consisting of nitroalkanes, oximes, and nitrates and nitrites of alkali metals, magnesium, ammonium, and copper.

9. The process for producing a bright copper electroplate which comprises electrodepositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.01 to 20 millimoles per liter of an alkali-soluble selenium compound selected from the group consisting of selenides, selenites, selenates, and selenocyanates, and from about 0.1 to about 10 grams per liter of 2-butyne-l,4-diol.

10. The process for producing a bright copper electroplate which comprises electrodepositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.01 to 20 millimoles per liter of an alkali-soluble selenium compound, from 1 to 200 millimoles per liter of a water-soluble acetylenic compound, and from about 0.05 to about 0.5 gram per liter of an alkali-soluble nitrile.

11. The process for producing a bright copper electro plate which comprises electrodepositing copper from an aqueous alkaline cyanide copper plating bath in which there is dissolved from 0.01 to 20 millimoles per liter of an alkali-soluble selenium compound, from 1 to 200 millimoles per liter of a water-soluble acetylenic compound, and from about 0.05 to about 0.5 gram per liter of a nitrile selected from the group consisting of succinonitrile, dicyandiamide, p,p'-oxydipropionin-ile, p-sulfo propionitrile, potassium dicyanoguanidine, and sodium dieyanamide.

References Cited in the tile of this patent UNITED STATES PATENTS 2,694,677 Ostrow Nov. 16, 1954 2,770,587 Ostrow Nov. 13, 1956 2,825,684 Wernlund Mar. 4, 1958 FOREIGN PATENTS 874,100 Germany Apr. 20, 1953 925,490 Germany Mar. 3, 1955 OTHER REFERENCES Serial No. 331.456, Weiner (A.P.C.), Published July 13, 1943.

UNITED STATES PATENT OFFICE Certificate of Correction Patent No. 2,881,121 April 7, 1959 Donald G. Foulke et al. h It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Columns 3 and 4, line 28, Table I, second column thereof, tenth item, for

column 3, line 70, for organic read inorganic-; column 5, lines 47 to 52, Table II, second column thereof should appear as shown below instead. of as in the patent:

column 8, line 71, for has read was-; olumn 9, lines 26 to 28, the formula should appear as shown below instead of as in the patent:

column 10, line 60, list of references cited, under FOREIGN PATENTS, for 925,490 Germany Mar. 3, 1955 read -924,490 Germany Mar. 3, 1955.

Signed and sealed this 28th day of July 1959.

[SEAL] Attest:

KARL H. AXLINE, ROBERT C. WATSON,

Attestz'ng Oficer. Oommz'ssz'onei of Patents.

UNITED STATES PATENT OFFICE Certificate of Correction Patent No. 2,881,121 April 7, 1959 Donald G. Foulke et a1.

' It is hereby certified that error appears in the printed specification of the above numbered atent requiring correction and that the said Letters Patent should read as correcte below.

Columns 3 and 4, line 28, Table I, second column thereof, tenth item, for

onr-cwmxomown read cmc(cm) on ozon column 3, line 70, for organic read -inorganic; column 5 lines 47 to 52, Table II, second column thereof should appear as shown below of as in the patent:

column 8, line 71,)for has read was-; column 9, lines 26 to 28, the formula should appear as shown elow instead of as in the patent:

FI L-0 column 10 line 60, list of references cited, under FOREIGN PATENTS, for 925,490 Germany Mar. 3, 1955 read 924,490 Germany Mar. 3, 1955-.

Signed and sealed this 28th day of July 1959.

Attest:

KARL H. AXLINE, ROBERT C. WATSON, Attesti/ng Oflioer. O'ommz'ssz'oner of Patents. 

1. A PROCESS FOR PRODUCING A BRIGHT COPPER ELECTROPLATE WHICH COMPRISES ELECTRODEPOSITING COPPER FROM AN AQUEOUS ALKALINE CYANIDE COPPER PLATING BATH IN WHICH THERE IS DISSOLVED FROM 0.01 TO 20 MILLIMOLES PER LITER OF AN ALKALI-SOLUBLE SELENIUM COMPOUND AND FROM 0.005 TO 200 MILLIMOLES PER LITER OF A WATER-SOLUBLE ACETYLENIC COMPOUND. 